The present invention relates to truss-type brake beams for railway cars and, particularly, to truss-type brake beams as employed in truck-mounted brake assemblies, such as disclosed in U.S. Pat. No. 4,613,016, assigned to the assignee of the present invention.
The outstanding attribute of conventional, truss-type brake beams is the ability of these beams to resist bending during the application of braking force without requiring the use of excessively large structural components. It is important to note that these conventional brake beams are generally flat in shape, resulting in the unbalanced torque forces in the beams during brake applications. With the advent of truck-mounted brake assemblies, in which the brake cylinder device is mounted on the brake beam as opposed to mounting on the car body in conventional rigging arrangements, non-conventional or custom-designed brake beams were employed. These non-conventional brake beams were generally flat in shape, also. Because these non-conventional brake beams were required to support the weight of the brake cylinder, as well as the braking forces, heavy and rather cumbersome brake beams evolved which were expensive to manufacture. This severely limited the commercial viability of truck-mounted brake assemblies for railway cars.
More recently, truck-mounted brake assemblies have undergone design innovations to permit use of conventional, truss-type brake beams in order to enhance their commercial acceptance, one such design being that disclosed in the above-mentioned U.S. Pat. No. 4,613,016, the subject matter of which is incorporated herein by reference. In this design, a brake cylinder is located in the space between the compression and the tension members adjacent the strut bar that separates the beam compression and tension members. A force-transfer lever is pivotally attached to the strut bar, being connected at one end to the brake cylinder piston push rod and at the other end to a force-transmitting rod that transmits the brake cylinder force to the force-transfer lever of the opposite brake beam. It will be appreciated, therefore, that considerable space is required between the beam compression and tension members to accommodate both the brake cylinder and the force-transfer lever.
The space provided between the beam compression and the tension members, however, is limited by the proximity of other components of the truck to the compression and tension members, such as the truck bolster and the wheel/axle unit, between which the brake beam is operatively disposed. Accordingly, conventional flat-type truss beams are not completely satisfactory for use in these innovative truck-mounted brake assemblies, particularly where the installation requires a relatively large size brake cylinder.